It is known in unrelated art to use magnetic filtration to remove certain impurities from kaolin slurries. J. Iannicelli, "High Extraction Magnetic Filtration of Kaolin Clay", Preprint 76-H-7, AIME Annual Meeting, Las Vegas, Nev., Feb. 22-26, 1976, pp. 16, discloses the use of high extraction magnetic filtration to remove iron-stained anatase and quartz, hematite, mica, tourmaline, siderite and pyrite from kaolin.
In related art, it is known to use a continuous carousel high-gradient separator to produce a feed for a flotation pilot plant in which flotation is used to produce the final iron oxide concentrate, and furthermore, it is known to use this type of separator for producing high grade iron oxide concentrates. See D. R. Kelland and E. M. Maxwell, "Oxidized Taconite Beneficiation by Continuous High Gradient Separation", IEEE Trans. on Magnetics, Vol. MAG-11, No. 5, September 1975, pp. 1582-1584, and D. R. Kelland, "High Gradient Magnetic Separation Applied to Mineral Beneficiation", IEEE Trans. on Magnetics, Vol. MAG-9, No. 3, September 1973, pp. 307-310, respectively.
Additionally, it is known to use wet high-intensity magnetic separation as a preconcentrating step in the beneficiation of low-grade iron ore material. Exemplary of this type of prior art are U.S. Pat. No. 3,337,328 to Lawver and U.S. Pat. No. 3,502,271 to Hays. These patents require the use of magnetic separation prior to a flotation step.
Another patent of interest is U.S. Pat. No. 2,352,324 to Hubler which discloses an ore beneficiation process which uses a flotation step and a type of magnetic separation that requires conditioning weakly magnetic impurities with an inorganic reagent.
None of the prior art of which we are aware discloses a process for scavenging iron from tailings produced by flotation beneficiation of iron ore, in which wet high-intensity magnetic separation (WHIMS) is used for scavenging and in which this scavenging step is the first treatment of the iron ore with a magnetic separator. Furthermore, none of the prior art of which we are aware discloses a process that can be used to increase the iron recovery in operating and future flotation beneficiation plants and that will permit these plants to yield a more uniform output by leveling off the variations in the flotation process due to changes in ore characteristics.